Various technologies (e.g., communications, signal processing etc.) employ conversion systems to convert an input signal from one form to another, such as from analog-to-digital or from digital-to-analog. Many of these conversion systems have benefited from the use of modulation techniques, such as delta-sigma modulation, to achieve a high degree of accuracy in the conversion. Delta sigma modulation can be implemented in the analog or digital domain, employing noise shaping and, depending on the implementation, quantization.
Non-linearities or other errors can result when delta-sigma modulation is utilized in conjunction with analog-to-digital, digital-to-analog or digital-to-digital conversion. Many of such errors are attributable to process variations or other limitations in the analog circuits associated with the converters being used. One area of particular interest that employs conversions systems is telecommunications. In order to provide adequate levels of service, such as to accommodate increasing Internet-based demands, a variety of digital access solutions are being developed and improved. For example, Digital Subscriber Line (DSL) technology and variants thereof provide transport mechanisms for delivering high-bandwidth digital data. The increasing demands on the telecommunications industry to provide adequate bandwidth to accommodate user demands has prompted significant research and development into improving communications services, including both wired and wireless services.
In order to improve conversion systems for communications and other technologies, various techniques have been developed to compensate for the non-linearities and errors that tend to occur with the signal conversion process. For example, component mismatches can be corrected by traditional randomization techniques on the component to average out and minimize mismatch effects, or by the trimming of analog components. These approaches are generally expensive. Self-calibration techniques have also been developed, although such approaches tend to be intractable or otherwise too complicated and/or expensive for efficient implementation.